19: Tolerance And Auto-Immunity

Question 1

What factor from DCs facilitates generation of iTregs?

Answer 1

Retinoic acid

Question 2

Cell-intrinsic and cell-extrinsic modes of action of CTLA4

Answer 2

Cell-intrinsic: CTLA-4 engaged on a T cell -> terminate further activity of that T cell
Cell-extrinsic: CTLA-4 on Tregs binds to B7 on APCs -> blocks T cell activation

Question 3

Four methods of preventing autoimmunity

Answer 3

1. Immunological tolerance
2. Deletion by Fas/FasL
3. CTLA-4
4. Tregs

Question 4

Immune privileged sites

Answer 4

Eyes, brain, pregnant uterus, ovary, testes, adrenal cortex, hair follicles

Question 5

Two inhibitory cytokines used by Tregs

Answer 5

IL-10, TGF-B

Question 6

Genes with strongest association to auto-immunity

Answer 6

HLA genes (esp class II)

Question 7

Three methods microbes use to initiate autoimmune disorders

Answer 7

1. Molecular mimicry
2. Polyclonal activation
3. Release of hidden/cryptic Ags

Question 8

Molecular mimicry

Answer 8

viral Ag is structurally similar to self-Ags -> T cells will react to both self and non-self

Question 9

Two examples of molecular mimicry

Answer 9

Rheumatic fever -> strep + cardiac myosin

MS -> various virus + myelin basic protein

Question 10

Polyclonal activation

Answer 10

Non-specific overreactive antiviral immune response causes liberation of self Ags

Question 11

Release of hidden Ags

Answer 11

Tissue damage causes release of previously hidden epitopes

Question 12

SLE type of hypersensitivity

Answer 12

Type III

Question 13

Diagnostic test of SLE

Answer 13

Presence of anti-nuclear Abs

Question 14

RA type of hypersensitivity

Answer 14

Type IV

Question 15

Four cell types involved in RA

Answer 15

Th17 mainly, Th1, plasma cells, macrophages

Question 16

Rheumatic factor

Answer 16

Circulating IgM or IgG that reacts with Fc portion of circulating IgG